Hormonal Timing and Order of Metamorphic Change II

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09/24/15
Thienthanh Trinh
Mind Map by Thienthanh Trinh, updated more than 1 year ago
Thienthanh Trinh
Created by Thienthanh Trinh over 10 years ago
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Hormonal Timing and Order of Metamorphic Change II
  1. How is the timing of the orderly sequence controlled?
    1. Thyroid hormone!
      1. T4 is the prohormone; greater quantity and less potent
        1. Precursors MIT and DIT are combined to form T3 and T4 in the thyroid gland
        2. Gradual Increase in Thyroid Horone
          1. Different Tissues=Different Sensitivity to Thyroid (Diff. Threshold
        3. How do tissues maintain sensitivity to thyroid hormone?
          1. Receptors on Tissue
            1. Enzymes that deionize T4 into T3 to make thyroid hormone more potent are found in specific locations
            2. Thyroid Imbalance
              1. Hypothyroidism
                1. Causes: low iodine
                  1. High TRH (brain)
                    1. High TSH (Ant. Pituitary)
                      1. NoT4/T3 bc of no iodine
                        1. Diseases: Goiter, buildup of TSH (Ant. Pituitary), more thyroid producing cells
                2. Hyperthyroidism
                  1. Causes: autoimmune disorder; antibodies bind to thyroid stimulating receptors in thyroid gland
                    1. Low TRH (brain)
                      1. Low TSH (Ant. Pituitary)
                        1. High T4/T3
                          1. Diseases: Grave's Disease, increase in size of the gland due to binding of receptors
                  2. Hypothyroidism
                    1. Decreased rate of cell proliferation; increased duration; same # cells
                      1. Slowed cell migration
                        1. Little cell differentiation/synapses, increase in cell death
                    2. Hyperthyroidism
                      1. Increased rate of cell proliferation; decreased duration; less # cells
                        1. No effect on cell migration
                          1. Same amount of cell differentiation
                    3. Frog/Tadpole Metamorphosis
                      1. CRH (Hypothalamus)
                        1. TSH (Anterior Pituitary Gland)
                          1. T3 & T4 (Thyroid Gland)
                            1. Tissues
                              1. METAMORPHOSIS
                        2. PRH/PIH (Hypothalamus)
                          1. Prolactin (Ant. Pituitary Gland)
                            1. Tissues
                              1. GROWTH
                          2. Metamorphosis: Maturation of Hypothalamus
                            1. Immature Hypothalamus
                              1. A lot of prolactin, little thyroxin, no CRH
                              2. Mature Hypothalamus
                                1. A lot of thryoxin, little prolactin due to inhibitory PIH
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